Damar continued to serve as Dukat's adjutant as Dukat negotiated the entry of the Cardassian Union into the Dominion in 2373, a move Damar supported as he expected it would restore Cardassia to its rightful place as a major power. He participated in the assault force that captured the FederationstarbaseDeep Space 9 (renamed Terok Nor) at the end of that year, though he was disappointed that the Dominion's non-aggression pact with Bajor prevented them from going on to reclaim the planet. Always distrustful of the Jem'Hadar and the Dominion in general, Damar submitted a secret memorandum to Dukat suggesting that they poison the last stocks of ketracel-white if new supplies could not be secured. Somehow this memorandum was "lost" and subsequently found by the Jem'Hadar, inciting a fight in Quark's. (DS9: "Call to Arms", "Behind the Lines")

A few days later, Damar regained Dukat's favor and was promoted to the rank of gul for developing a way to neutralize the self-replicating mines blockading the Bajoran wormhole, using the station's deflector. However, he inadvertently disclosed this fact to station resistance elements during a moment of drunken camaraderie with Quark. Shortly after, he substituted for Odo in station security after the arrival of the Female Changeling on the station, and was responsible for arresting Rom for attempting to sabotage the station's deflector. Meanwhile, Damar continued to update Quark on the status of their efforts to deactivate the minefield. This information eventually reached Starfleet, where it hastened their launch of Operation Return. (DS9: "Favor the Bold")

As a Federation fleet prepared to move against the station, Dukat ordered Damar to convince Ziyal to speak with him after the two had an argument. Damar's effort ended badly, since he already resented Ziyal for Dukat's continued concern for her in spite of her defiant attitude. When the Dominion reinforcements disappeared inside the wormhole and the station was in danger of being retaken by Starfleet and Klingon forces, Damar killed Ziyal after learning she had aided the station resistance in sabotaging Terok Nor's weapons array. However, this had the opposite effect than what he had hoped, since Dukat refused to leave his daughter's body. Damar ended up fleeing the station with the rest of the Dominion forces without him. (DS9: "Sacrifice of Angels") It was later revealed that Damar was consumed with guilt over his murder of Ziyal and had trouble sleeping because of it. (DS9: "Statistical Probabilities")

Following Dukat's nervous breakdown and subsequent capture, Damar became the de facto head of Cardassia under Dominion rule. However, whereas Dukat was able to assert himself on an equal standing with Weyoun, Damar possessed neither Dukat's force of character nor his military genius. As a result, in the aftermath of their recent defeat Damar became little more than a figurehead for Weyoun. Shortly after Operation Return, Weyoun compelled Damar to call for peace talks with the Federation. The talks were a ploy to gain possession to the Kabrel system, needed for their war efforts, but despite realizing this fact the Federation chose to agree to their proposal in order to gain a respite. (DS9: "Statistical Probabilities")

Even though he was promoted to legate, Damar's authority within the Dominion diminished even further as the war dragged on into stalemate and he found Weyoun increasingly blaming him and the Cardassians for their failure to achieve victory. As Damar found himself powerless while the Cardassians gradually became a subjugated people in their own land, he began turning to kanar and dalliances with women as a way of forgetting his troubles. Unexpectedly in late 2375, Damar was visited by Dukat, his old mentor and friend. Damar arranged for Dukat to be surgically altered into a Bajoran, though he was unaware of Dukat's plans. Before he left, Dukat reminded Damar that the man who had boldly fought the Klingons by his side was still there, and that Damar could be that man again. (DS9: "'Til Death Do Us Part")

A few days later, Damar's situation worsened when he was forced to sign the Dominion's new alliance with the Breen Confederacy, which promised unspecified Cardassian territorial concessions to the Breen. He also realized that the Dominion, led by the Female Changeling, took a rather casual approach to the increasing death-toll on the side of the Cardassians which had reached the millions. As a further humiliation, Weyoun ordered that Damar submit his tactical suggestions to the Breen general ThotGor. With his hatred of the Dominion and his disgust with himself reaching a boiling point, Damar finally decided to take action. He helped Worf and Ezri Dax escape Cardassia Prime, and began planning a rebellion with his long-time friend Gul Rusot. (DS9: "'Til Death Do Us Part", "Strange Bedfellows")

With Rusot and a few trusted military commanders, Damar planned a surprise assault on the Dominion cloning facility on Rondac III, which Weyoun speculated was to prevent any further Weyoun clones from being created. He made his move after the allied forces' defeat at the Second Battle of Chin'toka, declaring his objective to free the Cardassian people from the Dominion. After the attack, Damar went into hiding in one of his rebel bases. He was replaced on Cardassia by Legate Broca. Recognizing that he and his former enemies now had a common cause, Damar requested aid from the Federation and was joined by Kira Nerys, Odo, and Elim Garak. Despite his and many of his troops' misgivings about working with a former member of the Bajoran Resistance, Damar recognized the value of Kira's knowledge of organizing resistance cells and followed her advice the best he could. Eventually, this caused him to kill Rusot, who could not come to terms with Kira's race and nationality and that she was put in charge. (DS9: "The Changing Face of Evil", "When It Rains...", "Tacking Into the Wind")

Damar leading a Cardassian revolt against the Dominion

Unfortunately, despite some early successes, Damar's rebellion quickly received a nearly fatal blow by the Dominion. He, Kira, and Garak became trapped on Cardassia Prime, while the organized resistance was wiped out. Taking up shelter inside Garak's childhood home, they realized that Damar had risen to legendary status amongst the downtrodden Cardassian population. This allowed them to spark a planet-wide popular uprising, by making Damar into the "hero" who the Dominion had failed to kill. The Dominion responded to the insurrection by annihilating Lakarian City, which only served to add even more fuel to the rebellion. The extermination of the citizens of Lakarian City was the last straw: it turned the Cardassian military against the Dominion and caused the Cardassian fleet to defect during the Battle of Cardassia.

In the last days of the war, Damar was killed while leading an assault on Dominion Headquarters. Damar's last orders were to keep fighting, but he died mid-sentence. His death made him a martyr for the cause of Cardassian liberation, and both Elim Garak and Kira Nerys honored his final order by taking Dominion Headquarters, killing Weyoun and apprehending the Female Changeling. (DS9: "The Dogs of War", "What You Leave Behind")

Damar had a wife and a son. Though he was known to entertain at least one mistress after becoming the head of the Cardassian government, he nevertheless cared about both of them deeply. He sent his family into hiding as he began his rebellion, but the Female Changeling ordered them found and executed. This heinous act further fueled Damar's anger towards the Dominion. (DS9: "Penumbra", "Tacking Into the Wind")

A group of genetically-engineered Humans used a holographic recording of Damar to help uncover a move by the Dominion to acquire a strategic planet that would have allowed them to produce ketracel-white.(DS9: "Statistical Probabilities")

According to the script for "Apocalypse Rising", Damar's name was pronounced as "dah-MAR". [1]

Damar was played by Casey Biggs. The part was written, in "Return to Grace", as deceptively simple. "When I went to read for the role," Biggs recalled, "I thought to myself, 'What's the big deal? They could have gotten one of the extras to play this part.'" Much to the delight of "Return to Grace" Director Jonathan West, Biggs accepted the role despite it seeming minimalist. (Star Trek: Deep Space Nine Companion, pp. 308 & 309)

Jonathan West made Casey Biggs aware that Damar would have more to do in the future. "I guess the writers had this whole arc planned in their heads," reckoned Biggs, "because the first day of the shoot, Jonathan West came up to me and said, 'I don't want you to get nervous or anything, but they have big plans for this character.' I said, 'Why did you have to tell me this right now – just before my first shot, my first day in all this makeup!'" (Star Trek: Deep Space Nine Companion, pp. 308-309)

Through West's directing of "Return to Grace", he proceeded to reaffirm the importance of the Damar character. "I gave him close-ups," said West, "and took the time to get reactions from him, almost as if, from the audience's point of view, he was registering the value judgments on what was going on." (Star Trek: Deep Space Nine Companion, p. 309)

After completing work on DS9 Season 6, Weyoun actor Jeffrey Combs theorized, "I suspect that at some point Damar will be enamored by Dukat's return." Combs went to speculate that, together with Dukat, Damar would turn against Weyoun. (Cinefantastique, Vol. 30, No. 9/10, p. 69) Indeed, Dukat and Damar's final conversation may have sown the seeds that to Damar forming a rebellion against the Dominion.